Conventional external mirror arrangements for vehicles include a holder extending from and fastened to the side of the vehicle body. The holder is often a U-shaped bracket equipped with a lower and an upper, horizontally running support arm. The bracket and its free ends are pivotally linked to the vehicle body. One or more external mirrors are installed on the U-shaped bracket. The mirrors may be a flat main mirror and a convex, wide angle mirror. A drawback with these conventional mirror arrangements is that due to their relatively large dimensions and the correspondingly heavier mirror, especially for commercial vehicles, it is difficult to make the holder both highly stable and vibration-free.
One attempt to stabilize the conventional holder is to use a tie-bar support as shown for example in U.S. Pat. No. 5,880,895. This tie-bar support is coupled on one end to a mirror mounting arm at an external point spaced apart from a swivelable attachment point on the vehicle. The tie-bar support is swingably attached to the vehicle body on another end behind the point where the mirror mounting arm is installed. Thus, with the mirror mounting arm coupled to the tie-bar, a rigid triangular reinforcement structure is formed to stabilize the holder.
In certain situations, the mirror holder must be folded in to the vehicle body to drive the vehicle through a very narrow passage, for instance, or when the vehicle is undergoing a lengthy maintenance period. Thus, folding the mirror back in such situations protects the mirror from damage. Additionally, it is desirable for the mirror holder to be deflected inwardly if contact is possible with oncoming vehicles.
In order to both stabilize and fold back the mirror, the coupling between the tie-bar and the corresponding support arm must be releasable. When the coupling is released, the added support for the holder is removed and the holder can swing inward toward the vehicle body.
Certain known releasable couplings between the tie-bar and the support arm are often heavy and troublesome to recouple. Other releasable couplings such as the arrangement provided in U.S. Pat. No. 5,880,895 are made of plastic and rubber components, which frictionally engage each other and are thus vulnerable to weather and wear.